Content you delete from public view remains visible in your own feed, and you as a user cannot change that AFAIK. Maybe some app or browser frontend has the option to hide self-delete content?

Admins can “purge” a post or comment from the database, which would do what you are asking. But we try to avoid purging things if it isn’t absolutely necessary. It’s an irreversible process and a ripe opportunity for us to break things.